Fatoldlady
Lots of "old wives tales" about cures for cramp! I often get it, in any and every muscle possible it seems. Calf cramp is easy, out of bed, foot flat on the floor - gone. The absolute worst is the adductor (inner thigh) so very hard to stretch out. I once had cramp in both adductors and fainted from the extreme pain. Even in one it is excruciating. I'm currently trying to make sure I stay well hydrated, and as I sweat loads in the heat, I'm having electrolyte drinks too.
I'm not surprised you fainted - cramp in even your calves is excrutiating. Make yourself stretch out that calf - foot flat to the floor - I had this as a child & Mum told me to do this & it always works, regardless of age (although I get soreness after now which I didn't at 6).
Quinine is probably the best to try - works for the people I know- can be prescribed via a phone to GP so why do you need to see them? Nothing that can be gained in this scenario from an examination.
Mg actually really helps my Restless Legs (which I don't mind personally, being a deep sleeper, but it makes my allergy fatigue / muscle aches much worse when it's persistent).